DNA Extraction from Strawberry Kiwi DNA Lab objectives

DNA Extraction from Strawberry & Kiwi

DNA Lab objectives n I will extract DNA from the fruits that we eat such as strawberry and kiwi by following DNA extraction protocol. (Steps) n I will explain the purpose of each step in the extraction procedure as it relates to the physical and biochemical characteristics of cells.

onion strawberry banana peas broccoli Calf thymus Wheat germ University of California Davis Partnership for Plant Genomics Education 2007 kiwi

Some questions to get you thinking about today’s lab: One way to purify a molecule is to get rid of everything but that molecule. If we want to isolate DNA from strawberry/kiwifruit, what do we have to get rid of? What materials would you use to do that? What can we do with the DNA once we’ve purified it?

Three Main Steps in DNA Extraction n Break apart cells n Release DNA from nucleus n Precipitation of the DNA

Protocol 1. Get 4 pieces of kiwi/strawberry and put them in a ziplock bag. 2. Add 20 ml of extraction solution to the ziplock bag. Make sure the bag is closed without much extra air. Mush the strawberry/kiwi thoroughly but carefully so the bag doesn’t break, for about 5 minutes. What does mushing the kiwi do?

3. What do you think the extraction solution is? What does it do to the kiwi/strawberry?

5. Filter the mixture through the coffee filter. All the groups can combine their mixtures at this point, to filter together. Put 2 ml of the filtered juice in a test tube. What is being filtered out? What is going through the filter?

7. Being careful not to shake the tubes, add approximately 2 -3 ml of cold 95% ethanol to each tube. What do you think the ethanol does? Why do we want it cold? 8. Take a look at your tube. What do you see in the top portion of the liquid?

9. Place a stirring rod into the first tube and gently wind the DNA onto it. Be careful not to mix the ethanol and soapy layer. 10. Carefully remove the rod from the tube after winding as much DNA as possible on the stick.

Discussion Questions n Where can DNA be found in the cell? n What is DNA? n What are three basic steps in any DNA extraction? n What is the purpose of the detergent? Of the sodium chloride? Of the alcohol? n Describe the appearance of your final product. Is this a pure DNA sample? n List some practical applications where extracting DNA is necessary.